Marine air conditioning units must not only withstand harsh maritime conditions such as salt spray, mould and humidity, but also serve as vital equipment ensuring the normal operation of personnel and machinery. Their performance directly impacts crew working conditions, making reliability and maintainability paramount.
   The refrigeration unit employs a welded structure for structural integrity, with insulation comprising glass wool and galvanised perforated baffle plates. Key refrigeration components are designed for stable and reliable operation. The unit's return air damper utilises a turbine-type regulating valve with graduated display for convenient and flexible adjustment.
  Structural Design: The compressor and condenser are stacked vertically, arranged front-to-back in an integrated configuration. The compressor is positioned above the condenser, with components sequentially arranged from front to rear: mixing chamber, filter, evaporator, expansion valve, electric heater, fan, and outlet plenum. Airflow follows a U-shaped path. Automatic control components, instrument panels, and electrical control boxes are mounted laterally. The overall structure is compact, facilitating operation and maintenance. Refrigeration System Design: As the core of the entire unit, the refrigeration system employs a single semi-hermetic compressor due to its modest cooling capacity. To facilitate capacity modulation, a dual liquid supply system is utilised, comprising two solenoid valves and two expansion valves. The evaporator features a dual-circuit design, while the suction line operates as a single circuit. The condenser adopts a horizontal shell-and-tube configuration. The evaporator employs copper tubing with copper fins. Given the requirement for marine air conditioning units to maintain high external residual pressure, a marine direct-drive high-pressure centrifugal fan is utilised for air delivery.